"""
判断三角形
"""
a, b, c = input().split()
a, b, c = int(a), int(b), int(c)
flag = True
if a + b <= c:
    flag = False
elif a + c <= b:
    flag = False
elif b + c <= a:
    flag = False
if flag:
    print('yes')
else:
    print('no')